Randomize memory content to mimic real hardware

Author: smokku

ext/firmware

@@ -4,6 +4,7 @@
 
 #include "firmware/src/ria/cgia/font_8.h"
 
+#include <stdlib.h>
 #include <string.h>  // memcpy, memset
 
 #ifndef CHIPS_ASSERT
@@ -26,6 +27,10 @@ void x65_init(x65_t* sys, const x65_desc_t* desc) {
     }
 
     memset(sys, 0, sizeof(x65_t));
+    for (int i = 0; i < X65_RAM_SIZE_BYTES; i++) {
+        sys->ram[i] = rand() & 0xFF;  // fill RAM with random data
+    }
+
     sys->valid = true;
     sys->running = false;
     sys->joystick_type = desc->joystick_type;

src/systems/x65.c

@@ -110,6 +110,8 @@ typedef enum {
 #define X65_IO_TIMERS_BASE (0xFF88)
 #define X65_IO_RIA_BASE    (0xFFC0)
 
+#define X65_RAM_SIZE_BYTES (1 << 24)  // 16 MBytes of RAM
+
 // config parameters for x65_init()
 typedef struct {
     x65_joystick_type_t joystick_type;  // default is X65_JOYSTICK_NONE
@@ -145,7 +147,7 @@ typedef struct {
         float sample_buffer[X65_MAX_AUDIO_SAMPLES];
     } audio;
 
-    uint8_t ram[1 << 24];  // 16 MBytes of general RAM
+    alignas(64) uint8_t ram[X65_RAM_SIZE_BYTES];
     alignas(64) uint32_t fb[CGIA_FRAMEBUFFER_SIZE_BYTES / 4];
 } x65_t;